Improved detection limits of protein optical fiber biosensors coated with gold nanoparticles
Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Canada K1S 5B6. Electronic address: . Biosensors & Bioelectronics
(Impact Factor: 6.41).
09/2013; 52C:337-344. DOI: 10.1016/j.bios.2013.08.058
The study presented herein investigates a novel arrangement of fiber-optic biosensors based on a tilted fiber Bragg grating (TFBG) coated with noble metal nanoparticles, either gold nanocages (AuNC) or gold nanospheres (AuNS). The biosensors constructed for this study demonstrated increased specificity and lowered detection limits for the target protein than a reference sensor without gold nanoparticles. The sensing film was fabricated by a series of thin-film and monolayer depositions to attach the gold nanoparticles to the surface of the TFBG using only covalent bonds. Though the gold nanoparticle integration had not yet been optimized for the most efficient coverage with minimum number of nanoparticles, binding AuNS and AuNC to the TFBG biosensor decreased the minimum detected target concentrations from 90nM for the reference sensor, to 11pM and 8pM respectively. This improvement of minimum detection is the result of a reduced non-specific absorption onto the gold nanoparticles (by functionalization of the external surface of the gold nanoparticles), and of an optical field enhancement due to coupling between the photonic modes of the optical fiber and the localized surface plasmon resonances (LSPR) of the gold nanoparticles. This coupling also increased the sensitivity of the TFBG biosensor to changes in its local environment. The dissociation constant (Kd) of the target protein was also characterized with our sensing platform and found to be in good agreement with that of previous studies.
Available from: Jiang Li
- "The physical mechanism for the improved nonlinearity can be explained from two aspects: one is that the nonlinear refractive index of YAS is larger than that of silica . The other is that the nanoscale itself can improve the nonlinear coefficient . Moreover, compared with the silica optical fibers doped with noble metal nanoparticles, the scatting loss in this optical fiber is lower because the YAS is glass. "
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ABSTRACT: We design and fabricate a silica optical fiber doped with yttrium aluminosilicate (YAS, Y2O3–Al2O3–SiO2) nanoparticles in the core. The optical fiber is drawn directly from a silica tube with YAG(Y3Al5O12) ceramics and silica powders (the molar ratio 1:18) in the core at the temperature of �1950 �C. The YAS nanoparticles are formed during the optical fiber drawing process. Supercontinuum (SC) generation in the optical fiber is investigated at different pump wavelength. At the pump wavelength of �1750 nm which is in the deep anomalous dispersion region, SC spectrum evolution is mainly due to multiple solitons and dispersive waves (DWs), and three pairs of multiple optical solitons and DWs are observed. When the pump wavelength shifts to �1500 nm which is close to the zero-dispersion wavelength (ZDW), flattened SC spectrum with ±7 dB uniformity is obtained at the wavelength region of �990–1980 nm, and only one obvious soliton and DW are observed. At the pump wavelength of �1100 nm, a narrow SC spectrum from �1020 to 1180 nm is obtained in the normal dispersion region due to selfphase modulation (SPM) effect.
Available from: Aitor Urrutia
- "One of the latest steps in the search for improved novel sensors is the inclusion of nanoparticles (NPs) within coatings . In diverse new researches, it has been demonstrated that selected NP-embedded coatings enhance some parameters of previous devices, for example, sensitivity  , dynamic range, robustness, and lifetime. On one hand, these improvements are due to the fact that NPs can provide additional special properties in coatings (mesoporosity, higher roughness , antibacterial behavior, etc.). "
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ABSTRACT: The use of nanoparticles (NPs) in scientific applications has attracted the attention of many researchers in the last few years. The use of NPs can help researchers to tune the physical characteristics of the sensing coating (thickness, roughness, specific area, refractive index, etc.) leading to enhanced sensors with response time or sensitivity better than traditional sensing coatings. Additionally, NPs also offer other special properties that depend on their nanometric size, and this is also a source of new sensing applications. This review focuses on the current status of research in the use of NPs within coatings in optical fiber sensing. Most used sensing principles in fiber optics are briefly described and classified into several groups: absorbance-based sensors, interferometric sensors, fluorescence-based sensors, fiber grating sensors, and resonance-based sensors, among others. For each sensor group, specific examples of the utilization of NP-embedded coatings in their sensing structure are reported.
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ABSTRACT: Abstract Compounds routinely used to increase the quality of life and combat disease undergo stringent potency and biosafety tests before approval. However, based on the outcome of ongoing research, new norms need to be effected to ensure that the compounds conform to biosafety at all target levels of activity. Whereas in vitro tests used to assess biosafety lack the potency and the translational attribute of a whole animal, mammalian preclinical models are expensive and time exhaustive. Zebrafish (Danio rerio) has emerged as an attractive alternative for biosafety studies due to its small size, genetics, breeding capabilities, and most importantly, similarity at the molecular and physiological levels with humans. It has been used extensively for testing various forms of toxicity, including developmental toxicity, cardiotoxicity, nephrotoxicity, and hepatotoxicity. We review here the utility of zebrafish as a powerful, sensitive, quantitative, noninvasive, and high-throughput whole-animal assay to screen for toxicity. Different forms of toxicity will be discussed briefly before we highlight the present state of genotoxicity study in zebrafish. This review, a first in this research area, will serve as a comprehensive introduction to the field of genotoxicity assay using zebrafish, a nascent but promising field that assays compounds for DNA damage. We also discuss possible approaches that could potentially be pursued to overcome some of the shortcomings in current genotoxic studies.
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